I am a huge fan of flight simulation games (and aircraft mechanics in general), and this is a question that has always been interesting to me. Why are some crafts able to fly in super cold areas without freezing over and inevitably plummeting, while others have basically no chance of staying airborne?
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I’m going to toss in my 2 cents just to make sure rotorcraft are represented.
On a larger military helicopter like the H-60 or H-53, there are multiple anti-ice/de-ice features.
First some terms:
Anti-ice: Prevent ice from forming in the first place
De-ice: Remove ice that has already formed.
Most ice systems are anti-ice in nature. Some of these may also serve to de-ice if needed, but are best used before ice has formed.
Here are the types of ice systems on a helicopter:
Engine Anti-Ice: This system injects hot engine bleed air into the engine inlet to keep ice from building up on the compressor.
Pitot-tube Heater: Keeps the pitot-tube from building up ice, which can result in invalid airspeed measurement
Rotor blade de-ice: This is a system of heating elements installed on the leading edges of main and tail rotor blades, similar to the heating elements on the leading edge of airplane wings. It can prevent ice from forming and can remove some ice if it has already built up.
So far, this isn’t too different from a fixed wing aircraft. There are a few interesting items just for helicopters:
1) Rotor blade de-ice has to be used very carefully. The heating pads take up a much larger percentage of the space on a rotor blade than they do on a wing of an airplane. They are typically only turned on for a little bit at a time. There is typically an electronic component that cycles them on and off. Run them too much and they can burn holes in the blades. On an H-60, all four main rotor blades combined weigh only 400 pounds, for an aircraft that has a takeoff weight of 22,000 pounds. There isn’t much surface area to start burning holes in blades.
2) Ice buildup on the wing of an airplane can impact lift and add weight. Ice buildup on a rotor blade is similar. However, there is an extra danger for rotor blades. As ice forms, or even as it falls off, it can throw off the balance of the rotor system. This can cause significant vibrations and even lead to damage. Enough imbalance can lead to dynamic instability of the rotor system, which is just a fancy way of saying that the rotor violently destroys itself. There is even a scary sounding term for how blade de-ice systems can cause instability in the rotor system: “Asymmetrical Ice Shedding”.
There are limits to these systems. Many helicopters are not rated to fly in icing conditions at all, and for those with the necessary ice systems, they are often rated only to fly in areas that might experience light to medium icing.
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